The term "panel assemblies" as used refers to transparent, semi-transparent, opaque, and like panels framed by a gasket for incorporation in vehicle bodies or structures. Such panel assemblies typically comprise panels of window glass, however may include automobile taillight assemblies, decorative panels and the like.
Modern panel or window assemblies for use in automobiles are typically of two varieties. The first are modular or encapsulated window assemblies where the perimeter of the transparent panel has a gasket molded around it. The second type, referred to as laced window assemblies, utilize a gasket which is produced separately and then either attached to the perimeter of the panel or placed within the vehicle window mounting channel prior to mounting of the window. In either type of window assembly, the gasket serves as an interface between the window glass and the window mounting channel or surface of the vehicle body.
The gasket is typically a polymeric material such as EPDM rubbers (terpolymer of ethylene, propylene and diene monomers), polyvinyl chloride, olefinic polymers, thermosetting polymers, urethane, thermoplastic urethanes and thermoplastic elastomers. EPDM rubber is most commonly used for laced window assembly gaskets. Reaction injection molded (RIM) urethane and polyvinyl chloride are most commonly used for modular window assembly gaskets.
The gasket materials used today, especially the urethane used in modular window assemblies, are relatively stiff, having a tensile modulus at 100% elongation from about 1,000 to about 50,000 psi. The recent trend in using stiffer gaskets was prompted by the deficiencies inherent in the softer gasket materials known in the prior art, such as EPDM rubber. The softer materials do not provide and maintain as good a seal between the vehicle interior and external environment as do today's stiffer materials. Secondly, gaskets formed from softer materials are not as aesthetically appealing as stiffer materials in view of resulting bulges, shape deformation and irregularities in the softer material upon weathering, once the window assembly is mounted in the vehicle.
Various squeaks and other undesirable noises are often generated around such window assemblies, regardless of the gasket material used. The generation of such noises is believed to result from differing degrees of rigidity between the window assembly and the vehicle body, primarily at the interface between the vehicle body and the window assembly. This behavior is particularly evident as the vehicle body shifts, torques or vibrates from uneven road surfaces or changes in the vehicle's velocity. The importance of suppressing such unwanted noises has become of increasing importance to auto manufacturers.